Absence of paradoxical thrombin activation by fibrin-specific thrombolytics in acute myocardial infarction: comparison of single-bolus tenecteplase and front-loaded alteplase

Complications of Intravenous Tenecteplase Versus Alteplase for the Treatment of Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

BACKGROUND

Prior systematic reviews have compared the efficacy of intravenous tenecteplase and alteplase in acute ischemic stroke, assigning their relative complications as a secondary objective. The objective of the present study is to determine whether the risk of treatment complications differs between patients treated with either agent.

METHODS

We performed a systematic review including interventional studies and prospective and retrospective, observational studies enrolling adult patients treated with intravenous tenecteplase for ischemic stroke (both comparative and noncomparative with alteplase). We searched MEDLINE, Embase, the Cochrane Library, Web of Science, and the www.

CLINICALTRIALS

gov registry from inception through June 3, 2022. The primary outcome was symptomatic intracranial hemorrhage, and secondary outcomes included any intracranial hemorrhage, angioedema, gastrointestinal hemorrhage, other extracranial hemorrhage, and mortality. We performed random effects meta-analyses where appropriate. Evidence was synthesized as relative risks, comparing risks in patients exposed to tenecteplase versus alteplase and absolute risks in patients treated with tenecteplase.

RESULTS

Of 2226 records identified, 25 full-text articles (reporting 26 studies of 7913 patients) were included. Sixteen studies included alteplase as a comparator, and 10 were noncomparative. The relative risk of symptomatic intracranial hemorrhage in patients treated with tenecteplase compared with alteplase in the 16 comparative studies was 0.89 ([95% CI, 0.65-1.23]; I2=0%). Among patients treated with low dose (<0.2 mg/kg; 4 studies), medium dose (0.2-0.39 mg/kg; 13 studies), and high dose (≥0.4 mg/kg; 3 studies) tenecteplase, the RRs of symptomatic intracranial hemorrhage were 0.78 ([95% CI, 0.22-2.82]; I2=0%), 0.77 ([95% CI, 0.53-1.14]; I2=0%), and 2.31 ([95% CI, 0.69-7.75]; I2=40%), respectively. The pooled risk of symptomatic intracranial hemorrhage in tenecteplase-treated patients, including comparative and noncomparative studies, was 0.99% ([95% CI, 0%-3.49%]; I2=0%, 7 studies), 1.69% ([95% CI, 1.14%-2.32%]; I2=1%, 23 studies), and 4.19% ([95% CI, 1.92%-7.11%]; I2=52%, 5 studies) within the low-, medium-, and high-dose groups. The risks of any intracranial hemorrhage, mortality, and other studied outcomes were comparable between the 2 agents.

CONCLUSIONS

Across medium- and low-dose tiers, the risks of complications were generally comparable between those treated with tenecteplase versus alteplase for acute ischemic stroke.

Fibrinogen depletion and intracerebral hemorrhage after thrombolysis for ischemic stroke: a meta-analysis

PURPOSE

Intracerebral hemorrhage (ICH) can be a fatal complication of intravenous thrombolysis (IVT) for acute ischemic stroke. An early coagulopathy can develop after IVT, in relation to a significant fibrinogen depletion, increasing the risk of ICH. This systematic review and meta-analysis aimed at defining the role of fibrinogen depletion after IVT on the risk of ICH after IVT.

METHODS

Protocol was registered with PROSPERO (CRD42020124241) and followed PRISMA and MOOSE guidelines. We systematically searched English studies reporting rates of post-IVT ICH depending on fibrinogen depletion until 7/1/2021. Primary outcome was symptomatic ICH (sICH). Meta-analysis followed random-effects model to account for heterogeneity in design and timing of ascertainments. Biases were assessed via the Newcastle-Ottawa Scale.

RESULTS

Overall, among 352 records identified, 5 observational studies were eligible for quantitative synthesis (n = 2142), all of fair quality. Considering sICH within 24-36 h post-IVT, pooling data from 4 studies (n = 1753), fibrinogen depletion consistently increased the risk of sICH (OR 3.67, 95%CI 2.28-5.90, p_{heterogeneity} = 0.55). Pooling adjusted estimated for age, gender, and NIHSS from 3 studies (n = 723), fibrinogen depletion was confirmed to significantly increase the risk of ICH after IVT (OR 5.41, 95%CI 2.96-9.89).

CONCLUSIONS

Fibrinogen depletion significantly increases the risk of ICH after IVT for acute ischemic stroke. Routine fibrinogen assessment might be considered to identify people at higher risk of ICH. As fibrinogen repletion is feasible, trials should investigate its efficacy in preventing ICH, potentially increasing the net benefit profile of IVT in acute ischemic stroke.

Adjunctive Intracoronary Fibrinolytic Therapy During Primary Percutaneous Coronary Intervention

Despite routinely restoring epicardial coronary patency, with primary percutaneous coronary intervention (PCI), microvascular obstruction affects approximately half of patients and confers an adverse prognosis. There are no evidence-based treatments for microvascular obstruction. A key contributor to microvascular obstruction is distal embolisation and microvascular thrombi. Adjunctive intracoronary fibrinolytic therapy may reduce thrombotic burden, potentially reducing distal embolisation of atherothrombotic debris to the microcirculation. In this review, the evidence from published randomised trials on the effects of adjunctive intracoronary fibrinolytic therapy during primary PCI is critically appraised, the ongoing randomised trials are described, and conclusions are made from the available evidence. Clinical uncertainties, to be addressed by future research, are highlighted.

Tenecteplase Thrombolysis for Acute Ischemic Stroke

Tenecteplase is a fibrinolytic drug with higher fibrin specificity and longer half-life than the standard stroke thrombolytic, alteplase, permitting the convenience of single bolus administration. Tenecteplase, at 0.5 mg/kg, has regulatory approval to treat ST-segment-elevation myocardial infarction, for which it has equivalent 30-day mortality and fewer systemic hemorrhages. Investigated as a thrombolytic for ischemic stroke over the past 15 years, tenecteplase is currently being studied in several phase 3 trials. Based on a systematic literature search, we provide a qualitative synthesis of published stroke clinical trials of tenecteplase that (1) performed randomized comparisons with alteplase, (2) compared different doses of tenecteplase, or (3) provided unique quantitative meta-analyses. Four phase 2 and one phase 3 study performed randomized comparisons with alteplase. These and other phase 2 studies compared different tenecteplase doses and effects on early outcomes of recanalization, reperfusion, and substantial neurological improvement, as well as symptomatic intracranial hemorrhage and 3-month disability on the modified Rankin Scale. Although no single trial prospectively demonstrated superiority or noninferiority of tenecteplase on clinical outcome, meta-analyses of these trials (1585 patients randomized) point to tenecteplase superiority in recanalization of large vessel occlusions and noninferiority in disability-free 3-month outcome, without increases in symptomatic intracranial hemorrhage or mortality. Doses of 0.25 and 0.4 mg/kg have been tested, but no advantage of the higher dose has been suggested by the results. Current clinical practice guidelines for stroke include intravenous tenecteplase at either dose as a second-tier option, with the 0.25 mg/kg dose recommended for large vessel occlusions, based on a phase 2 trial that demonstrated superior recanalization and improved 3-month outcome relative to alteplase. Ongoing randomized phase 3 trials may better define the comparative risks and benefits of tenecteplase and alteplase for stroke thrombolysis and answer questions of tenecteplase efficacy in the >4.5-hour time window, in wake-up stroke, and in combination with endovascular thrombectomy.

Elevated international normalized ratio as a manifestation of post-thrombolytic coagulopathy in acute ischemic stroke

BACKGROUND

A serious complication of intravenous tissue plasminogen activator (tPA) in acute ischemic stroke is hemorrhage. Coagulation factors that may potentially increase the risk of bleeding after tPA are not well understood.

METHODS

We retrospectively reviewed 284 acute ischemic stroke patients who received tPA. Post-tPA coagulopathy was defined as a documented elevation of international normalized ration (INR) > 1.5 within 24 hours after IV tPA without a known cause.

RESULTS

We identified 21 (7.4%) patients with an elevated INR post-thrombolysis. The mean age was 68.3 years (standard deviation ± 11.9) and 57% were male. The mean initial National Institutes of Health Stroke Scale (pre-tPA) was 15.8 (range, 4-35). Liver disease or alcohol abuse was noted in 19%. There were 2 tPA protocol violations who received more than 90 mg tPA. The mean post-tPA INR was 2.03 (range, 1.5-4.7) and the elevation in INR was documented within a mean 5.4 hours (range, 1-15) after tPA initiation. Repeat INR levels returned to normal during their hospital stay in 19 patients. Hypofibrinogenemia was noted in 10 of 12 patients who had fibrinogen levels drawn within 48 hours after tPA initiation and in all 7 patients with fibrinogen levels drawn the same time as the elevated INR. Among the 6 patients with bleeding complications, 2 patients had symptomatic intracerebral hemorrhage.

CONCLUSIONS

We report an under-recognized early transient coagulopathy associated with elevated INR in stroke patients after treatment with tPA.

Off-target effects of thrombolytic drugs: apolipoprotein A-I proteolysis by alteplase and tenecteplase

The administration of thrombolytic drugs is of proven benefit in a variety of clinical conditions requiring acute revascularization, including acute myocardial infarction (AMI), ischemic stroke, pulmonary embolism, and venous thrombosis. Generated plasmin can degrade non-target proteins, including apolipoprotein A-I (apoA-I), the major protein constituent of high-density lipoproteins (HDL). Aim of the present study was to compare the extent of apoA-I proteolytic degradation in AMI patients treated with two thrombolytic drugs, alteplase and the genetically engineered t-PA variant tenecteplase. ApoA-I degradation was evaluated in sera from 38 AMI patients treated with alteplase or tenecteplase. In vitro, apoA-I degradation was tested by incubating control sera or purified HDL with alteplase or tenecteplase at different concentrations (5-100 μg/ml). Treatment with alteplase and tenecteplase results in apoA-I proteolysis; the extent of apoA-I degradation was more pronounced in alteplase-treated patients than in tenecteplase-treated patients. In vitro, the extent of apoA-I proteolysis was higher in alteplase-treated sera than in tenecteplase-treated sera, in the whole drug concentration range. No direct effect of the two thrombolytic agents on apoA-I degradation was observed. In addition to apoA-I, apoA-IV was also degraded by the two thrombolytic agents and again proteolytic degradation was higher with alteplase than tenecteplase. In conclusion, this study indicates that both alteplase and tenecteplase cause plasmin-mediated proteolysis of apoA-I, with alteplase resulting in a greater apoA-I degradation than tenecteplase, potentially causing a transient impairment of HDL atheroprotective functions.

Intrapleural hemorrhage after administration of tPA: a case report and review of the literature

OBJECTIVE

Intrapleural fibrinolytic enzymes have been used for over 60 years in the treatment of complicated pleural effusions to lyse loculations and promote resolution. Despite this extensive history of use, however, little is known about complications that may arise with the use of this therapy. Here we discuss a patient with chronic renal failure on hemodialysis who developed an intrapleural hemorrhage after the administration of intrapleural tPA to treat a complicated parapneumonic effusion. A review of the literature examines the efficacy and safety of this therapy, focusing on bleeding complications. Specific attention is paid to patients who have underlying coagulopathies or who are receiving anticoagulation.

DATA SOURCES

A review of the literature, as indexed in PubMed, was undertaken using the following search terms in combination: tPA, pleural effusion, complications of thrombolytics, and intrapleural hemorrhage. The search was inclusive of patients under the age of 18, but was limited by English language and human subjects.

STUDY SELECTION/DATA EXTRACTION

All relevant articles identified during the search were reviewed. Those studies that reported on bleeding complications, or lack thereof, were included in this review. Limitations of each article are noted in the text.

CONCLUSIONS

Multiple studies, including a 2000 ACP consensus statement and a 2008 Cochrane review, indicate the need for further investigations to evaluate the safety and efficacy of intrapleural thrombolytics for the treatment of complicated pleural effusions and empyemas. Limited studies specifically address bleeding complications, especially in subpopulations of patients receiving concurrent anticoagulant therapy.

Specific types of activated Factor XII increase following thrombolytic therapy with tenecteplase

BACKGROUND

Activated Factor XII (XIIa) is believed to participate in a number of pathophysiological processes including inflammation, thrombosis and fibrinolysis. Increasing XIIa levels following thrombolytic therapy have previously been reported. In contrast to other thrombolytics, tenecteplase (TNK-tpa) does not show paradoxical thrombin activation, indicating a lower procoagulant effect of this fibrin-selective thrombolytic agent. Recent research has demonstrated that in-vivo XIIa exists in a number of different types, and the aim of this study was to investigate plasma variations of different types of XIIa following thrombolytic treatment with TNK-tpa.

METHODS

Citrated blood samples were obtained from 34 patients admitted with acute ST-elevation myocardial infarction (STEMI) treated with TNK-tpa. Samples were taken immediately prior to treatment, 30-90 min after and 4 days post-treatment. XIIa measurements were performed using 2 ELISA assays designed to preferentially measure different types of XIIa; XIIaA and XIIaR. Both assays utilised a monoclonal antibody 2/215, which is highly specific for XIIa, as the solid phase capture antibody. The assay for XIIaA used a conjugate based on a polyclonal antibody against the entire XIIa molecule, whilst the assay for XIIaR incorporated a reagent to release otherwise unavailable XIIa and used a conjugate based on a monoclonal antibody against beta-XIIa.

RESULTS

Changes in plasma XIIaA concentration as a result of therapy were more evident than changes in XIIaR concentration. XIIaA showed a significant increase from 67.1 (49.0-84.4) pM to 97.8 (75.5-133.1) pM [median and 25 and 75% percentiles] in the 30-90 min sample (P < 0.001), returning to pre-intervention levels 61.5 (47.5-81.0) pM by day 4. In contrast, no significant change in XIIaR concentration was observed following thrombolytic therapy with TNK-tpa.

CONCLUSION

In patients admitted with STEMI, thrombolytic therapy with TNK-tpa resulted in a significant short-lasting increase in specific types of XIIa (namely XIIaA), whereas other types of XIIa (XIIaR) were largely unaffected by this intervention.

Combined Thrombolysis with Abciximab Favourably Influences Platelet-Leukocyte Interactions and Platelet Activation in Acute Myocardial Infarction

BACKGROUND

In patients with acute myocardial infarction (AMI), activated platelets and altered haemostatic/fibrinolytic systems with and without thrombolytic therapy are known. Platelets thereby interact with neutrophils, stimulated endothelial cells and with monocytes leading to adverse effects on further myocardial damage. Thrombolysis in these patients is still hampered by procoagulant effects favoring early reocclusion. The additional treatment with a GPIIb/IIIa antagonist aimed to minimize early reocclusion thus improving the present therapeutic regimen.

METHODS

In 38 patients with AMI, we investigated the effects of a thrombolytic regimen with half reteplase (r-PA) dose plus abciximab vs. full dose r-PA on membrane-bound adhesion molecules (CD41, CD42b, CD40, CD40L) expressed on platelets, neutrophils and monocytes as well as on soluble platelet-selectin as interaction and activation markers of these cells.

RESULTS

The combination group had significantly (p < 0.05) lower sP-selectin levels over 48 h vs. the group treated with full dose r-PA. After 3 h, the percentage of CD41 and CD42b positive monocytes and granulocytes as well as the percentage of CD40 positive granulocytes and the percentage of CD40L positive monocytes markedly (p < 0.01, p < 0.05) decreased in the combination group vs. data at admission compared with the r-PA group indicating less leukocyte-patelet adhesion.

CONCLUSIONS

The thrombolytic regimen with half dose r-PA and abciximab had a benefical influence on platelet activation and induced a more marked decrease of platelet-monocyte, and in part, platelet-granulocyte aggregates compared with the r-PA regimen. This could contribute to a probably lesser monocyte activation state with favourable effects on monocyte-endothelial adhesion and a consecutively possible influence of myocardial damage, a reduction of the additionally acute local inflammatory processes and a reduction of adherence of platelet-granulocyte aggregates to subendothelium.

Potential In Vitro Interaction Between Tenecteplase and Unfractionated Heparin

STUDY OBJECTIVE

To explore the potential of a direct drug interaction between unfractionated heparin (UFH) and tenecteplase that lowers the pharmacologic propensity of UFH to prolong the activated partial thromboplastin time (aPTT).

DESIGN

In vitro experiment.

SETTING

Texas Tech University School of Pharmacy, with sample analysis performed at an independent, contract laboratory. Samples. Blood samples collected from healthy volunteers.

INTERVENTION

Three separate in vitro experiments were conducted to explore the relative influence of various thrombolytic agents with and without UFH on aPTT prolongation. In each experiment, blood from healthy volunteers (12 for each experiment) was treated with different concentrations and combinations of tenecteplase and UFH.

MEASUREMENTS AND MAIN RESULTS

When the effects of tenecteplase plus UFH versus UFH alone on aPTT prolongation were compared, each experiment demonstrated attenuation of aPTT with the combination versus UFH alone. In contrast, findings for other thrombolytic agents combined with UFH demonstrate elevation of the aPTT compared with UFH alone.

CONCLUSION

The results indicate a possible drug interaction between tenecteplase and UFH, with tenecteplase attenuating the intensity of anticoagulation of UFH in vitro. Further investigation into this possible interaction is warranted in the clinical setting.